JPH032042B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for refining a water-soluble polymer gel. More specifically, the method involves crushing a water-soluble polymer gel obtained by polymerizing an aqueous solution of a water-soluble vinyl monomer, and then further pulverizing it into fine particles using a vertical cutting machine consisting of a fixed blade and a rotating blade. Regarding.

[Prior Art] Conventionally, acrylamide homopolymers, copolymers mainly composed of acrylamide with other polymerizable monomers, or alkaline hydrolysates thereof have been used as paper strength agents and thickeners. It is widely used as a soil conditioner, crude oil recovery agent, wastewater treatment agent, etc.

Methods for producing these water-soluble acrylamide polymers include bulk polymerization, suspension polymerization, emulsion polymerization, and solution polymerization, but it is important to produce polymers with essentially high molecular weight. Therefore, aqueous solution polymerization is often used.

In order to obtain a polymer with a very high molecular weight and good water solubility using the water-soluble polymerization method, it is necessary to carry out the polymerization at a relatively low concentration in order to prevent crosslinking during the polymerization reaction stage. There is.

However, in recent years, economic efficiency such as transportation costs and storage costs has become important, and powder products have become the mainstream of production rather than liquid products. When the polymer is powdered, a large amount of water must be volatilized and dried, which has the disadvantage of increasing the utility cost for powdering.

In order to eliminate such drawbacks, research has been conducted to reduce utility costs in the powdering stage by polymerizing at the highest possible monomer concentration, and numerous patent petitions have been filed.

However, vinyl monomers such as acrylamide and acrylic acid inherently have a very strong tendency to crosslink and become three-dimensional. Regarding the concentration, for example, in the case of anionic or nonionic polymers, the polymerization must be carried out while maintaining a relatively low concentration of about 20 to 30% (weight %, same hereinafter) at most.

When acrylamide or a monomer solution mainly consisting of acrylamide at the above concentration is polymerized, a hard or highly elastic gel-like material with no fluidity is obtained. Therefore, for example, if you try to volatilize the water contained in a mass or sheet of gel polymer without mechanically crushing it, you will have to leave it under high temperature for a very long time. As a result, the molecular weight of the high-molecular-weight polymer that has been painstakingly produced decreases, and crosslinking of the polymer due to thermal changes is promoted, resulting in a significant decrease in commercial value. Therefore, generally obtained polymer gel lumps or sheets are crushed by some mechanical means into small agglomerated particles, and then
A method of removing water by drying by heating is used. Generally, a method is widely adopted in which a polymer gel obtained by polymerization is formed into a strand shape using an extrusion molding machine such as a meat grinder, and then heated and dried. However, when using an extrusion molding machine such as a meat grinder, especially when the polymer gel is extremely hard, the friction on the machine wall is large, which not only causes a loss of machine efficiency.
This is not a very preferable method because the polymer gel itself is subject to deterioration due to frictional heat, physical forces, etc., resulting in a decrease in molecular weight due to molecular cleavage.

The present inventors have proposed a method for crushing a polymer gel obtained by polymerizing an aqueous solution of a water-soluble vinyl monomer, which does not involve a decrease in molecular weight and allows the crushed polymer gel into pieces to mutually interact. We developed a method to prevent adhesion and filed a patent application on November 6, 1981 (title of invention: "Method for crushing water-soluble polymer gel", hereinafter referred to as
(referred to as A application).

However, the strip-shaped polymer gel obtained by the method according to the above application is a relatively large angular polymer gel of 3 to 20 mm, and even if you try to dry it by heating in this state, the inside of the polymer gel It is difficult for the moisture present in the material to volatilize. As a result, the drying time becomes longer and the volume required for drying (hereinafter referred to as drying capacity) inevitably increases.

It can be easily inferred that in order to reduce the drying capacity, the polymer gel particles before drying should be made as small as possible and the drying time should be shortened. With an extrusion molding machine such as an extrusion molding machine, it is absolutely impossible to refine the polymer gel into angular particles having a size of 3 to 20 mm.

[Problems to be Solved by the Present Invention] The present invention provides crushed polymer gel as described above,
This is done in order to solve the problem that if the polymer gel is coarse, it is not easy to heat dry it by further making the polymer gel cut into square shapes of preferably 3 to 20 mm finer and drying it. It is something that

[Means for solving the problem] When the present inventors made the polymer gel into fine particles,
As a method to prevent the fine particles from adhering to each other, polymerization is carried out while keeping the aqueous solution of water-soluble vinyl monomer as high as possible, and when necessary, an anti-adhesive agent is used when refining the particles. blowing cold air, changing the crushing format,
As a result of extensive research on these issues, we have arrived at the present invention.

That is, in the present invention, after crushing a polymer gel obtained by polymerizing an aqueous solution of a water-soluble vinyl monomer, a fixed blade and a rotating blade are used to crush a region in which the polymer gel to be crushed remains. further cutting the crushed polymer gel with a rigid cutter having an average crushing residence time of at least 3 minutes;
The present invention relates to a method for refining a water-soluble polymer gel, which is characterized by refining the particles.

[Example] Examples of water-soluble vinyl monomers used in the present invention include water-soluble vinyl monomers such as acrylamide, methacrylamide, acrylic acid, methacrylic acid, vinylsulfonic acid, acrylamide-methylpropanesulfonic acid, and itaconic acid. (meth)acrylic acid dialkylaminoalkyl esters, salts or acidic salts thereof, or quaternized products thereof, dialkylaminoalkylacrylamides, salts or acidic salts thereof, or quaternized products thereof, diallylamine acid salts , diallylamines such as diallylalkyl ammonium salts, etc., but are not limited to these. These may be used alone, or 2
More than one species may be mixed and used.

The water-soluble vinyl monomers include monomers that are essentially insoluble in water to the extent that the resulting polymer is water-soluble, such as acrylonitrile, (meth)
Hydrophobic monomers such as acrylic esters, vinyl acetate, and styrene may also be blended.

There are no particular limitations on the method of polymerizing the water-soluble vinyl monomer, such as thermal polymerization using a radical polymerization initiator such as a known persulfate or an azo initiator, a method using known persulfates/amines, or Common methods include a redox polymerization method using a redox polymerization initiator such as persulfate/sulfite, a photopolymerization method using a photopolymerization initiator such as benzoin or benzoin alkyl ether, or a radiation polymerization method. Generally, by such a method, an aqueous solution of a water-soluble vinyl compound at a predetermined concentration is polymerized until it no longer flows freely. When polymerizing an aqueous solution of a water-soluble vinyl monomer as described above by irradiating ultraviolet rays, especially when the aqueous solution is formed into a thin film and irradiating it with ultraviolet rays, the induction time for polymerization is very short, and The time required for polymerization is shorter than other methods. As a result, the equipment required for polymerization is compact and equipment costs are low. Further, it is preferable to select the polymer in a continuous and thin layer form using a movable support, since this has the advantage that subsequent crushing and pulverization can be made continuous.

It is preferable for the polymer gel obtained using water-soluble vinyl monomers to have as high a concentration as possible from the viewpoint of improving productivity. It is also preferable from the viewpoint of prevention. In general, nonionic or anionic polymer gels obtained using acrylamide or acrylic acid have a content of 20 to 60%, preferably
30 to 45%, while in the case of cationic polymer gels using dialkylaminoalkyl acrylate or its acid salts or quaternary salts, it is 50 to 90%.
%, preferably 60-80%.

In order to efficiently cut the polymer gel with a pair of roller-type cutters that rotate in a mutually interlocking direction as described in the A application specification, the polymer gel must be smoothly embedded into the roller-type cutters. Therefore, the thickness of the polymer gel is preferably 2 to 30 mm, preferably 5 to 15 mm. For example, when a water-soluble vinyl monomer aqueous solution is polymerized using a container such as a dish, flat plate, or tray type, or a movable belt, it can be formed into a thin layer. The method of polymerizing in a thin layer on a movable belt is a preferred method because it can be continuous with the subsequent crushing step.

In the present invention, the polymer gel obtained as described above is crushed using a crusher as described in the specification of the A application, an embodiment of which is shown in FIGS. It is preferably crushed into square pieces of 3 to 20 mm.

If the size of the crushed material exceeds an average particle size of 20 mm, the cutting ability in the next step of vertical cutting tends to decrease, and it is difficult to forcibly cut polymer gel with an average particle size that is too coarse, exceeding 20 mm. If too much material is supplied to the vertical cutter, poor cutting will occur, and agglomerates of polymer gel will form inside the cutter, at the same time frictional heat due to adhesion will be generated, creating an undesirable vicious cycle.

The polymer gel is fed to the crusher from above the crusher as shown in FIG. 4, for example. The supplied polymer gel is cut by roller type cutters 13 and 14 shown in FIG. 6, which is a top view of the crusher shown in FIGS. 4 and 5, and is cut into, for example, short strands. Ru.

On the surfaces of the roller type cutters 13 and 14, as shown in FIG. 6, more specifically, in FIG. 7, cutter blades are formed in a concave and convex shape so that the concave and convex portions engage with each other. These interlocking roller-type cutters have, for example, the same dimensions and
Rotate in the direction of engagement at the same rotational speed. The width, depth, and height of the unevenness of the blades formed to interlock with each other are the size desired for the crushed polymer gel.
In other words, it is sufficient to determine the average grain size to be 3 to 20 mm. For example, in Fig. 8, width X ₁ is 2 to 10 mm.
The depth of the concave part of the blade x ₄ is about 10 to 15 mm, and the height of the convex part of _the blade is about 10 to 15 mm. The gap (X ₃ in FIG. 8) necessary for the passage of the combined gel is usually formed to be about 10 to 20 mm. Roller type cutter 1 in this shape
5 (C-C' cross section in FIG. 4) As shown in the figure, the polymer gel can be easily cut into strands by biting and cutting the polymer gel supplied from above and feeding it downward. Can be done.

In order to supply the polymer gel to the roller type cutters 13 and 14, the polymer gel is continuously taken out from the other end of a movable support, for example, an endless belt, and then fed into the roller type cutters 13 and 14. By doing so, the process can be made continuous and production efficiency can be improved.

The polymer gel strands cut into short pieces, for example, by the roller type cutters 13 and 14 rotating in the interlocking direction, are cut into the roller type shown in FIG. 7 by the upper edges of the combs 15 and 16 shown in FIG. It is peeled off from the outer periphery of the cutter blade A,
It descends between the comb 15 and the comb 16 and reaches the position of the fixed blade 12 provided at the lower end of the comb 16.
Normally, the polymer gel strands do not stick to the outer blade B of a roller type cutter. The short strand-shaped strand that reaches the position of the fixed blade 12 and comes out below the position is the rotary blade 1 provided on the outer periphery of the rotating body 10 with the rotation axis 7 in FIGS. 4 and 5.
1 and the fixed blade 12, the material is cut into strips, preferably rectangular strips with an average particle diameter of 3 to 20 mm.

The cross-sectional shape of the short piece in the width direction is based on the machine dimensions of the roller cutters 13 and 14 after assembly,
That is, it is determined by the width X ₁ of the unevenness of the blade, the depth of engagement X ₂ , the heights X ₄ and X ₅ and the rotational speed of the roller type cutters 13 and 14 in FIG.
The longitudinal shape of the short strips is determined by the rotational speed of the roller-type cutters 13 and 14, the rotational speed of the rotary body 10 that rotates at a speed synchronized therewith, and the number of rotary blades 11 provided on the rotary body 10. By adjusting the number of pieces (6 pieces in Figure 5), the length to be cut into strips can be determined.

Next, the crushed polymer gel, preferably 3-
We will explain the cutting machine and method used to finely granulate the polymer gel crushed into 20 mm square shapes.

FIG. 1 is a schematic top view of the main parts of a vertical cutter used for finely pulverizing the crushed polymer gel used in the present invention, and FIGS. 2 and 3 are cross-sectional views. It is.

In FIG. 1, 1 is a rotary blade, 2 and 2' are the first and second fixed blades, 3 is a pre-cutter, 4 is a screen, 5 is a rotation axis of the rotary blade 1,
6 is a bottom surface, and 7 is a discharge hole.

The vertical cutting machine used in the present invention shown in FIG.
It has a retention area C that circumscribes the area with Do, has a half-moon shape when viewed from above, and allows retention for at least 3 minutes, and has a drive rotation axis (axis 5 of the rotary blade in Figures 1 and 2). is facing vertically upward,
In other words, it is a vertical point.

In Fig. 3-1, among the angular polymer gels of 3 to 20 mm to be supplied, as shown in Fig. By rotating the cutting blade at the tip of the fixed pre-cutter 3, a polymer gel having a relatively large inner diameter of 10 to 20 mm among the 3 to 20 mm angular polymer gels is crushed.

At this time, the first point of the method of the present invention is that the polymer gel having a square shape of 3 to 20 mm is supplied (dropped) from the axis of the shaft 5 of the rotary blade toward the shaft 5 of the rotary blade. By doing so, the polymer gel having a coarse diameter can be selectively converged to a diameter range of 3 to 5 mm. The 3-20 mm angular polymer gel thus supplied is first aligned to 3-5 mm. The polymer gel cut into pieces in the range of 3 to 5 mm in this way is placed in the first section in the main body of the vertical cutting machine.
It is inserted into a gap of 1 mm or less between the first fixed blade 2 assembled as shown in the figure and the rotating rotary blade 1, and is cut at the same time as it is inserted. The cut polymer gel has an arc-shaped screen 4 when viewed from above.
The area a surrounded by the outer peripheral end of the rotating rotary blade 1, the first fixed blade 2, and the second fixed blade 2' is moved along the rotating direction of the rotary blade 1 to the second fixed blade 2'. .

The second point of the method of the present invention is that among the cut polymer gels moving within the area a, polymer gels having a diameter smaller than the pore diameter Ds of the screen 4 are scattered outward due to centrifugal force. , passes through the pores of the screen 4, is discharged from the region a to the discharge hole 7, and is separated from the polymer gel which is coarser than the pore diameter Ds of the screen.

On the other hand, among the cut polymer gels that are moving in the area a, the polymer gels with a diameter larger than the pore diameter Ds of the screen 4 are again moved to the second fixed blade 2' as shown in FIG. After being pinched by the rotary blade 1 and cut, it enters along the rotational direction of the rotary blade 1 into a region b surrounded by the rotary blade 1 and a circumference drawn by an arc having the same diameter as the screen 4 . And area b
The polymer gel moving is again caught in the gap between the first fixed blade 2 and the rotary blade 1 and cut, and the same cutting is repeated thereafter.

In this way, a diameter of 3 to 20 mm of the polymer gel supplied (falling) from above the axis of the rotating shaft 5 of the vertical cutting machine to the rotating shaft 5 located below the vertical cutting machine is discharged from the vertical cutting machine. The particles are separated into particles smaller than the hole diameter Ds of the screen 4 through the holes 7, and are continuously discharged, allowing for desired cutting. At this time, screen 4
The larger pores are cut by the second fixed blade 2' and the rotary blade 1 as described above to reduce the diameter of the polymer gel, but thirdly, the larger pores in area b This means that the cut polymer gel that has penetrated into the stagnation region stagnates in the retention region c. Thereafter, on average at least 3
The polymer gel remaining for a minute is cut once again by the fixed blades 2, 2' and the rotary blade 1 by rotation of the rotary blade, and the above-mentioned cutting process is repeated. The average residence time exceeds at least 3 minutes, and the polymer gel retained in the retention area c is subjected to the granulation effect due to extremely vigorous mixing and stirring due to the centrifugal force of the rotary blade 1, and becomes rounded. As a result, the shape of the particles in the dried powder product approaches the desired spherical shape.

As described above, the method of the present invention has the desirable effect of not only refining the crushed polymer gel but also making the shape of the refined polymer gel closer to a spherical shape.

The vertical cutter used in the present invention is a typical commercially available, and unlike general crushers such as Feather mill and Huitu mill, it can maintain the average crushing residence time of the material to be crushed at 3 minutes or more.
A homogeneous fine-grained gel is obtained because the polymer gel is discharged with a very small number of cuts without undergoing multiple cuts. The structure of the cutting machine is characterized by adjusting the gap between the vertical fixed blades 2, 2' installed vertically inside the cutting machine and the rotary blade 1, and changing the hole diameter Ds of the sieve. , and by arranging multiple vertical cutting machines in series,
That is, by passing through the cutting machine two to several times, it is possible to control the residence time of pulverization, making it easy to cut into polymer gels with small particle sizes, for example, 1 mmΦ or less. . Another point is that the shape of a polymer gel with a small particle size of 1 mm or less has the desirable effect of approaching a sphere. A technique for refining crushed polymer gel using a vertical cutting machine having such a structure has not been established in the past.

For example, in the first step, if you cut using a cutting machine equipped with a 3mmΦ screen, it will be approximately 3mmΦ.
A unified finely divided polymer gel can be obtained as follows. Next, in the second step, the particles are finely divided using a cutting machine equipped with a 2 mm Φ screen, and in the third step, they are refined using a cutting machine equipped with a 1 mm Φ screen, resulting in fine grains that are uniform in diameter of approximately 1 mm Φ or less and have a rounded appearance. Particles are obtained. By selecting a screen suitable for the target particle size in this way, the target particle size can be obtained.

In addition, when the method of the present invention is adopted, almost no dust is generated during the step of refining the polymer gel, which is essentially in a wet state, and particles with a uniform particle size and a particle size distribution close to monodisperse can be obtained. available.

When crushing the polymer gel to make it fine particles, in order to increase the cutting efficiency and prevent the resulting fragmented polymer gel and the finely divided polymer gel from re-adhering, It is preferable to keep the temperature of the polymer gel as low as possible during cutting.

Methods for lowering the temperature of the polymer gel include cooling sufficiently during the polymerization stage when crushing it into small pieces, and cooling the polymer gel obtained by polymerization by blowing cold air etc. before crushing it with a crusher. This can be achieved by forcible cooling, but it is generally preferred to adjust the temperature to 10 to 30°C, preferably 20°C or lower.

Furthermore, if the crushing process is cooled by blowing cold air, preferably cold air at a temperature of 25°C or less, for example, to produce short strands, and then cutting the strands into strips, the friction at the time of cutting It is possible to reduce the possibility that the polymer gel becomes sticky due to heat or the driving heat of a roller type cutter, or that the cut pieces of the polymer gel adhere to each other and become block-like.

In addition, when the polymer gel that has been made into fine particles is further made into fine particles, the crushed polymer gel that is to be made into fine particles may be forcibly cooled in advance, as in the case where the polymer gel is made into fine particles. , cold air when refining, preferably 25
If the granulation step is carried out while cooling, such as by blowing cold air at a temperature below .degree. C., the same effect as in the case of fine granulation can be obtained.

In addition, in the crushing and pulverization process, polyethylene glycol, nonionic surfactant,
By introducing anionic surfactant into a crusher or vertical cutting machine, or applying it to the surface of the polymer gel or the surface of the crushed polymer gel, it is possible to create strips of polymer gel or finely granulated polymer. It may also be used to prevent gel re-adhesion.

In carrying out the method of the present invention, an aqueous solution of a water-soluble vinyl monomer is polymerized in the form of a thin film on a movable support such as an endless belt to obtain a polymer gel, and the polymer gel is continuously polymerized in a 3 to 20 mm film. Crush into square shapes, then use a vertical cutting machine to reduce the average particle size to 0.3
When the grain size is reduced to about 3 mm, the entire process can be made continuous. Furthermore, if the ultraviolet irradiation method is used for polymerization, a polymer gel can be obtained in a short time, and if the crushing and granulation are carried out while blowing cold air at 25℃ or less, the crushing efficiency and granulation efficiency can be improved. Can be done.

Since the method of the present invention is a method for refining a polymer gel that is essentially in a wet state, when the method of the present invention is adopted, it is possible to use the generally used refining method under a dry state, that is, drying. Generation of fine powder due to dust generated when a polymer that has failed in the process is crushed in a dry state (hereinafter referred to as dry crushing), crushing heat generated during crushing, decrease in molecular weight due to crushing heat, water Disadvantages such as the occurrence of insoluble substances can be overcome.

More specifically, the vertical cutting machine used in the present invention has an average crushing residence time of at least 3 minutes and has a vertical structure, so it is not as effective as a commonly used crusher used in a dry state. Unlike the case where the grinding residence time is short, generation of fine powder can be prevented with the help of water contained in the polymer gel that is atomized in a wet state, and sufficient cutting time can be provided. This allows the particles to be refined to the point where they can maintain a uniform particle shape.

The particle size distribution of the fine particles obtained by the method of the present invention is almost monodisperse, and such a unique and excellent distribution could never be obtained by conventional methods.

In the case of cutting under wet conditions as in the present invention, unlike dry grinding, much of the heat generated during cutting and grinding is due to the abundant moisture contained in the polymer gel (for example, 30 to 70 %) of the latent heat of vaporization, resulting in a significant increase in the grinding temperature, thereby preventing deterioration of polymer quality, such as a decrease in molecular weight and the formation of water-insoluble substances.
As described above, the method of the present invention has a significantly superior advantage in terms of preventing quality deterioration. Therefore, compared to commonly used dry milling, the amount of heat generated during milling is replaced by the evaporation potential of the sufficient amount of water contained in the polymer gel, thereby increasing the milling temperature to undesirable levels. can be prevented. As a result, it is possible to eliminate unfavorable phenomena in terms of quality, such as deterioration of polymer quality, such as a decrease in molecular weight and the formation of water-insoluble substances.

Next, the method of the present invention will be explained based on examples.

Example 1 A polymerization device with a jacket (length 200 mm, width 300 mm, height 50
mm square container (without top lid) was installed. 200 g of acrylamide from which dissolved oxygen was sufficiently removed using nitrogen gas in a deoxidizing tank (cylindrical type with a capacity of 1)
was dissolved in 275 g of deionized water, 5 ml of 5% potassium persulfate aqueous solution and 5 ml of 5% sodium sulfite aqueous solution were added, and after continued deoxidation with nitrogen gas for several minutes, nitrogen gas was added. was introduced into the polymerization apparatus installed in a sealed room, and polymerization was started. Water at 25°C was passed through the jacket. Polymerization started after about 10 minutes, and the aqueous monomer solution gradually thickened. At the time point when 15 minutes had passed after the start of polymerization, the monomer aqueous solution was in a state of gently flowing.

Approximately 2 hours after the start of polymerization, the polymer became a hard gel. The polymer gel was approximately 8 mm thick.

The obtained polymer gel is crushed by a crusher as shown in Figs.
mm, depth of recess 10 mm, height of protrusion 10 mm, depth of engagement (gap required for polymer gel to pass through)
X ₃ ) 12mm, roller cutter surface speed 10.5
cm/min, and when the rotating blade is adjusted to a rotation speed of 20 to 100 r/min and crushed at 20°C, it is approximately 3 x 8 x 3 mm.
cut into squares. After that, cut into a vertical cutting machine as shown in Figures 1 to 3 from above about 3 x 8 x
Supply and drop a 3 mm square polymer gel, approximately 15
While blowing cold air at 100°C, cutting was performed using a vertical cutting machine equipped with a 3 mm Φ screen in the first stage, followed by a 2 mm Φ screen in the second stage, and a vertical cutting machine equipped with a 1 mm Φ screen in the third stage. In both cases, the average crushing residence time is approximately
It was hot in 3.2 minutes. As a result, a finely divided polymer gel having a diameter of approximately 1 mm was obtained.

When the obtained polymer gel with a diameter of about 1 mm was dried with hot air at 80°C, powder with a moisture content of 10°C or less and a uniform particle size was obtained in about 25 minutes. The powder has an intrinsic viscosity of 23
dl/g, resulting in an aqueous solution containing no water-insoluble substances, and was useful as a flocculant.

Comparative Example 1 When the 3 x 8 x 3 mm angular polymer gel obtained in Example 1 was dried with hot air at 80°C, it finally became a powder with a moisture content of 10% or less after about 60 minutes. It was a pellet-like powder and needed to be further crushed.

When the powder was crushed using a Fitzmill-type crusher having a screen of approximately 1 mmΦ, the generation of ultrafine powder of 100 mesh passes was significant (approximately 3.43%), resulting in a powder with a large amount of dust.

The intrinsic viscosity of the obtained powder product was 21.5 dl/g, and it was clearly a powder containing a large amount of water-insoluble substances.
Quality deterioration occurred during the drying and crushing stages.

Example 2 A stainless steel endless belt with a width of 450 mm and an effective length of 3000 mm, with a tetrafluoroethylene-ethylene copolymer film (thickness 50 μm) attached to the surface, was constructed to allow hot to cold water to be sprayed on the back side. The belt was placed as a movable support for polymerization in a chamber completely filled with nitrogen gas, moved at a constant speed of 30 mm/min, and the back side of the belt was sprayed with water at 25°C.

Approximately 30% aqueous N,N,N-trimethylaminoethyl methacrylate chloride monomer aqueous solution with a concentration of 75% adjusted to pH 4 with 10% aqueous hydrochloric acid was thoroughly degassed with tsutium gas and placed on the belt in operation for 10/hour. The feed was metered from one end of the belt at a speed.

In addition, 5% potassium persulfate solution and sodium sulfite solution were placed as polymerization initiators in two temporary storage tanks (5 volumes) equipped with a stirrer installed above the belt, and each was continuously supplied at a rate of 70 ml/hour. was added to the monomer aqueous solution while mixing, and supplied onto the belt while uniformly mixing.

Under the above conditions, polymerization started approximately 20 minutes after supply. The time during which the monomer aqueous solution was subjected to polymerization on the belt was 100 minutes, the monomer aqueous solution layer during polymerization was about 12 mm, and the total polymerization time was 2 hours.

120 minutes after the start of supplying the monomer aqueous solution, a sheet-like polymer with a thickness of about 12 mm was obtained from the other end of the endless belt. Continuous polymerization for about 3 hours was possible in a state where the obtained polymer belt could be easily peeled off by manual force from the surface.

The temperature of the thick gel obtained was about 28°C.

The polymer gel sheet continuously obtained from the other end of the endless belt is transferred to a crusher as shown in FIGS. 4 to 6 above roller-type cutters 13 and 14 rotating in the interlocking direction as shown in FIG. Continuously supplied from the crusher, crushed, approximately 5× from the crusher outlet
A 12×5 mm square polymer gel was obtained.

Thereafter, the angular polymer gel was fed into a vertical cutting machine as shown in FIGS. 1 and 2 from vertically above the shaft 5 of the rotary blade as shown in FIG. At this time, the diameter of the screen hole for the vertical cutting machine is 3mmΦ
I set up a screen that looks like this. Cut while blowing cold air of approximately 15℃ from above the vertical cutting machine.
Then, cutting was carried out using a cutting machine equipped with a 2 mmΦ screen and a 1 mmΦ screen to obtain a finely divided polymer gel having a size of about 1 mmΦ. In all cases, the average crushing residence time was about 3.5 minutes.

When the resulting finely granulated polymer gel with a diameter of about 1 mm was dried at 80°C in a ventilated band dryer, powder with a moisture content of 10°C or less was obtained in about 15 minutes.

The water solubility of the obtained granular material was that it contained no water-insoluble substances and had an intrinsic viscosity of 7.0 dl/g.

Comparative Example 2 When the angular polymer gel of about 5 x 12 x 5 mm obtained in Example 2 was dried under the same conditions as in Example 2, the moisture content decreased to below 10°C in about 40 minutes.
The aqueous solution of the dried product has an intrinsic viscosity of 6.8 dl/g,
Contains some water-insoluble substances.

Example 3 An endless belt made of stainless steel with a width of 450 mm and an effective length of 3000 mm was equipped with a tetrafluoroethylene-ethylene copolymer film whose back surface was vapor-deposited with aluminum, and hot to cold water was applied to the endless belt from below. A movable support for polymerization with a structure that can be sprayed was installed in a chamber completely filled with nitrogen gas, operated at a constant speed of 100 mm/min, and water at 15°C was applied from below the belt. was sprayed. In addition, a low-pressure mercury lamp is installed as an ultraviolet irradiation source on the top of the movable support to control the intensity of ultraviolet rays.
It was set to 50W/ ^m2 .

A 75% aqueous N,N,N-trimethylaminoethyl methacrylate chloride monomer aqueous solution adjusted to pH 4 with a 10% aqueous hydrochloric acid solution was thoroughly degassed with nitrogen gas, and was placed on the belt in an operating state for 13.5 hours. The feed was metered from one end of the belt at a speed.

Additionally, from a temporary storage tank (5 volumes) with a stirrer installed above the belt, add 30 ml of 5% methanol solution of benzoinpropyl ether as a polymerization initiator.
The monomer aqueous solution was supplied into the monomer aqueous solution at a rate of 1 hour, and polymerization was carried out by ultraviolet irradiation while uniformly mixing the monomer aqueous solution and the polymerization initiator.

Under the above conditions, the time during which the aqueous monomer solution was subjected to polymerization on the belt was 30 minutes, and the layer of the aqueous monomer solution during polymerization was about 5 mm.

Thirty minutes after the start of supplying the monomer aqueous solution, a sheet-like polymer having a thickness of 5 mm was obtained from the other end of the endless belt. The obtained polymer could be easily peeled off from the belt surface by hand, and continuous polymerization for about 3 hours was possible.

The resulting polymer gel was at 20°C.

The polymer gel sheet continuously obtained from the other end of the endless belt is transferred to a crusher as shown in FIGS. 4 to 6 above roller-type cutters 13 and 14 rotating in the interlocking direction as shown in FIG. The polymer gel was continuously supplied from the gel and crushed to obtain a 3 x 5 x 5 mm angular polymer gel.

Then, while passing cold air of about 15℃, it was heated to about 3mmΦ
Using a cutting machine as shown in FIGS. 1 to 3, which is equipped with a screen of Subsequently, it was cut through a cutting machine equipped with a screen of about 2 mmΦ and a screen of about 1 mmΦ in this order to obtain a finely divided polymer gel having a size of about 1 mmΦ. In all cases, the average crushing residence time was approximately 3.7 minutes.

When the resulting finely granulated polymer gel with a diameter of about 1 mm was dried at 80°C in a ventilated band dryer, powder with a moisture content of 10°C or less was obtained in about 13 minutes.

The resulting powder contained no water-insoluble substances and had an intrinsic viscosity of 7.8 dl/g.

Comparative Example 3 When the angular polymer gel of about 3 x 5 x 5 mm obtained in Example 3 was dried under the same conditions as in Example 3, the moisture content decreased to 10% or less in about 35 minutes.

The aqueous solution of the dried product has an intrinsic viscosity of 7.5 dl/g.
It contained some water-insoluble substances.

[Effects of the Invention] By using the method of the present invention, it is possible to continuously crush and refine the polymer gel, it is possible to make the polymer gel into extremely fine grains, and the fine particles of the polymer gel are mutually separated. As a result, the drying efficiency of the next process can be greatly increased.
The amount of fine powder in 100 meth is extremely small.
It can solve the problems of dust generation and dusting that were considered problems in the past.There is almost no decrease in the degree of polymerization or molecular weight when crushing or crushing the polymer gel (conventional methods cause a significant decrease in molecular weight, and improvements are required. ) The product (powder) obtained by pulverizing the polymer gel and drying it has a spherical shape.
It has the remarkable effect of improving the fluidity of the liquid.

[Brief explanation of the drawing]

Figures 1 to 3-1 are explanatory diagrams relating to one embodiment of the cutting machine used in the present invention; Figure 3-2 is an explanatory diagram showing only the structure of the screen used in Figure 3-1 in three dimensions; 4 to 6 are explanatory diagrams relating to one embodiment of a crusher for producing crushed pieces used in the present invention, and FIG. 7 is an explanatory diagram relating to the engaging portion of the roller type cutter shown in FIG. 6. FIG. 8 is an enlarged explanatory diagram for explaining in detail the meshing portion shown in FIG. 7. (Main symbols in the drawing), 1: rotating blade, 2: first fixed blade, 2': second fixed blade, c: retention area.

Claims (1)

[Claims] 1. After crushing a polymer gel obtained by polymerizing an aqueous solution of a water-soluble vinyl monomer, the blade is composed of a fixed blade and a rotating blade, and the polymer gel to be crushed remains. Refinement of a water-soluble polymer gel, characterized by further cutting the pulverized polymer gel using a vertical cutter having a pulverization area and an average pulverization residence time of at least 3 minutes, and pulverizing it into fine particles. Method. 2. Polymer gel obtained by polymerizing an aqueous solution of a water-soluble vinyl monomer into a thin film on a movable support is continuously crushed into squares of 3 to 20 mm, and then cut using a vertical cutting machine. The method according to claim 1, wherein the particles are refined to an average particle size of 0.3 to 3 mm. 3. The method according to claim 1 or 2, wherein the polymer gel is a polymer gel obtained by irradiating an aqueous solution of a water-soluble vinyl monomer in the form of a thin film with ultraviolet rays. 4. The method according to claim 1, 2, or 3, wherein the material is continuously crushed while passing cold air at 25° C. or lower to further refine the particles.